Various stents are known in the art wherein, for the present application, the term "stent" indicates a device, made of body-compatible material, which is utilized to widen a blood vessel, or other orifice in the body, and to maintain the resultant size of the lumen. Typically, the stent is delivered to the desired location in the body with an inflatable balloon and, when the balloon is inflated, the stent expands, thereby widening the orifice. Other mechanical devices which cause expansion of the stent are also utilized.
Exemplary patents in the field of stents formed of wire are: U.S. Pat. No. 5,019,090 to Pinchuk, U.S. Pat. No. 5,161,547 to Tower, U.S. Pat. No. 4,950,227 to Savin, et al., U.S. Pat. No. 5,314,472 to Fontaine, U.S. Pat. No. 4,886,062 and U.S. Pat. No. 4,969,458 to Wiktor and U.S. Pat. No. 4,856,516 to Hillstead. Stents formed of cut stock metal are described in: U.S. Pat. No. 4,733,665 to Palmaz, U.S. Pat. No. 4,762,128 to Rosenbluth, U.S. Pat. No. 5,102,417 to Palmaz and Schatz, U.S. Pat. No. 5,195,984 to Schatz and WO 91FR013820 to Meadox.
The stents described in U.S. Pat. No. 5,102,417 to Palmaz and Schatz have expandable tubular grafts connected together with a flexible connector. The grafts are formed of a plurality of slots disposed parallel to the longitudinal axis of the tube. The flexible connectors are helical connectors. Since the tubular grafts are relatively rigid, the flexible connectors are needed so that the stents can bend when being fed through a curved blood vessel. When the stents of U.S. Pat. No. 5,102,417 expand, the grafts expand radially and, consequently, shrink longitudinally. However, at the same time, the helical connectors twist. The twisting motion is most probably harmful to the blood vessel.
U.S. Pat. No. 5,195,984 to Schatz describes a similar stent but with one straight connector, parallel to the longitudinal axis of the tubular grafts, between tubular grafts. The straight member removes the twisting motion; however, it is not a very strong connector.